exp: 轮次50——门控20mm 的 seed=1 复现失败于幅度：时限收益 +6.25pp→+0.39pp，精度代价减小但未消除

两 seed 合并后必须更正轮次49 的一句话：到达题组内末态误差 vs 控制的符号检验 s0 67/57(p=0.419)、
s1 74/51(p=0.049)、合并 141差/108好 p=0.042 ⇒ 是"大幅减小"而不是"与控制不可分"。
中位数(+3.4%/+2.6%)与逐题分布给出相反印象，因为门控把尾部拉近中位、却把大量题各推一点。
到达两 seed 合并赢24丢21 净+3 p=0.766 ⇒ 这条轴上到达没有可用信号。

稳的部分：goal_ratio_2s 两 seed 都改善(0.170/0.201 vs 0.279/0.275) ⇒ "打分地平线=执行地平线"
买路上进度是唯一稳健效应。可推荐形态是 ungated pre，门控留给末态余量优先的场景。

统计自纠：精确 McNemar/符号检验原写法 2*Σ_{i<=min(k,n-k)}C(n,i)/2^n 在 k=n/2 中间点会算出 1.168>1；
改成 p=min(1,2*min(P(X<=k),P(X>=k))) 后重算本轮全部已上报 p 值，除中间点那例外数值不变
(0.125/0.424/0.678/0.455/0.327/0.042/4.9e-16/1.8e-12/2.4e-6 都对得上)，中间点正确值 p=1.0。

下一轮补 2×2 的缺失格 K16+pre 量可加性（已在盘三格），判读规则预注册。

docs/experiment_round50_gate20_s1.json

@@ -0,0 +1,110 @@
+{
+  "config": {
+    "ckpt": "ml/runs/base_dag2_dag1/best.pt",
+    "samples": "ml/data/samples",
+    "tasks": null,
+    "split": "val",
+    "n": 256,
+    "K": 8,
+    "commit": 2,
+    "fb": 2.2,
+    "ki": 0.0,
+    "fb_scale": 0.0,
+    "fb_near": 0.2,
+    "fb_fallback": 0.0,
+    "kdecay": 0.9,
+    "kimax": 0.5,
+    "fb_every": 1,
+    "safety_try": 0,
+    "sel_w": 0.1,
+    "dls_safety": 1,
+    "fb_clear": 0.0,
+    "fb_cmin": 0.3,
+    "sub_refresh": 0,
+    "fb_block_gain": 0.5,
+    "dump": "ml/runs/round50_gate20_s1_rows.json",
+    "out": "docs/experiment_round50_gate20_s1.json",
+    "trace": null,
+    "select": "pre",
+    "replan": "empty",
+    "safety": 1,
+    "partial": 1,
+    "inc_cap": 1,
+    "gap_margin": 0.0,
+    "cert_batch": 1,
+    "steps": 1,
+    "z_scale": 1.0,
+    "len_w": 0.0,
+    "tie": 0,
+    "pre_h": 0,
+    "pre_near": 20.0,
+    "backoff": 0,
+    "max_sec": null,
+    "seed": 1,
+    "dls": "analytic",
+    "device": "cuda"
+  },
+  "batch_size": 256,
+  "batch_seed_rule": "same seed per batch",
+  "checkpoint_sha256": "f7f686fd8ee92fb6948fbcc4ee954636065ad87bb54f661c4f8f575bc16c2ce1",
+  "tasks_sha256": "249bd93457825cda98c59e64d9a096d3473c69aeb3553de1dea6d9e56be71772",
+  "kin_fp": "2ebcbf17",
+  "act_scale": 1.0,
+  "metrics": {
+    "n": 256,
+    "n_ref": 256,
+    "success": 0.53125,
+    "collision_free_success": 0.53125,
+    "time_ok_1p3": 0.30078125,
+    "collision_rate": 0.0,
+    "collision_steps_mean": 0.0,
+    "travel_ratio_median": 2.6468124389648438,
+    "time_mean_s": 2.462352752685547,
+    "brakes_mean": 19.71875,
+    "start_fail": 0.0,
+    "goal_ratio_2s": 0.20109058916568756,
+    "err_fail_med": 177.47691345214844,
+    "err_success_med": 0.22864246368408203,
+    "dls_share": 0.6484375,
+    "time_budget": "teacher×2(≥3 s)",
+    "speed_ratio_p50": 1.0000016689300537,
+    "speed_ratio_p95": 1.0000101327896118,
+    "speed_ratio_max": 1.0000101327896118,
+    "over_vmax_rate": 0.0,
+    "accel_ratio_p95": 1.0000016689300537,
+    "accel_ratio_max": 1.0000101327896118,
+    "reverse_p50": 0.2363184094429016,
+    "reverse_mean": 0.24333104491233826,
+    "reverse_moving_p50": 0.28763440251350403,
+    "moving_share_p50": 0.9736841917037964,
+    "brake_rate_mean": 0.10112179815769196,
+    "brake_rate_p50": 0.0051282052882015705,
+    "brake_rate_p90": 0.35641026496887207,
+    "stuck_share": 0.24609375,
+    "n_plans_mean": 195.0,
+    "success_reachable": 0.5596708059310913,
+    "by_cat": {
+      "A": [
+        128,
+        94
+      ],
+      "B": [
+        74,
+        23
+      ],
+      "C": [
+        32,
+        12
+      ],
+      "D": [
+        13,
+        0
+      ],
+      "Dr": [
+        9,
+        7
+      ]
+    }
+  },
+  "simulation_wall_s": 271.2116083000001
+}